1. Field of the Invention
The present invention relates to the field of computer-aided design for sheet metal parts. More particularly, the present invention relates to recognizing patterns in sheet metal parts.
2. Background Information
The ability to recognize patterns in sheet metal parts would be useful. One use for pattern recognition is searching for similar parts. When designing a new 3D object (i.e., target object) on a computer-aided design (CAD) system, it is sometimes more efficient to start with a similar object and modify the similar object to create the desired object, rather than to design the new object from scratch. In order to start with the similar object, a user searches for an object having some type of similarity to the target object.
Many attempts have been made to find geometrical similarities of 3D solid objects. None of the previous attempts, however, have succeeded in recognizing patterns of sheet metal part models to enable accurate comparison of sheet metal parts due to the hollowness or emptiness of sheet metal shapes. For example, as shown in FIG. 1, it can be seen that two superimposed solid part models, which are not identical, share a large common area. Thus, an analysis would indicate that the models are similar. Similar superimposed sheet metal part models, however, do not have a large amount of overlap, as seen in FIG. 2. Thus, an analysis would indicate that the parts are not similar, when in fact they are similar.
In addition, directly comparing 3D geometries of part shapes is inaccurate and time consuming because such a geometric comparison of part shapes is very sensitive to size, orientations, etc. of shapes Thus, direct comparison often creates ambiguous search results.
Current systems, such as the system disclosed in U.S. Pat. No. 6,539,399 to HAZAMA et al., issued on Mar. 25, 2003, have a function for searching for similar sheet metal parts. However, the HAZAMA et al. system does not recognize patterns of sheet metal shapes and thus only searches by text such as “part name”, “updated date”, “material name”, “machine name,” etc. When the user wants to search parts by shape instead of text, for example, when a user only knows a cross section view of a part, or when a user only knows the flat shape, the HAZAMA et al. system has shortcomings.
Moreover, the input of search criteria in prior systems is inadequate. Previous search systems for sheet metal shapes used a complete sheet metal shape as a search key. This approach requires users to create a complete sheet metal part in order to perform a simple search. Finding a similar part model is no longer necessary because the exact part has been designed. If the user could merely specify cross sections or a 2D flat shape in order to search parts, it would be very useful and save time during manufacturing processes.